An announcement last Wednesday revealed an overall decline in cancer death rates -- probably due to reduced exposure to tobacco, early detection, and better treatment. But the announcement also revealed a surprising jump in cases of thyroid cancer for women. Between the years 1981 and 1993, incidence rates among women climbed 2.2 percent each year. Between the years 1993 and 2000, they rose 4.6 percent per year. And between 2000 and 2003, there was a 9.1 percent increase each year. This could be a result of better diagnosis but scientists are wondering if there is an unknown risk factor contributing to this startling finding. And it will take at least two more years to determine whether this is a random fluctuation or a true trend. The rate of thyroid cancer in men has also increased but not as much as for women.
The silver lining in this cancer cloud is that trends -- such as those showing increases in cancer incidences and death rates -- often fuel the fight against cancer because researchers are alerted to look for causes which ultimately results in better detection and better prevention.
1. Diagnostic criteria for thyroid tumours have changed: very small tumours used to be ignored because they are common and benign. Now they are called microcarcinoma, and the patient is counted as cancer. This change lead to what a French study jokingly calls “an epidemic of microcarcinomas” (references below).
This explains the puzzling increase in incidence, but decrease in mortality, from thyroid cancer.
EM, in Canada
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed
Posted at 4:50PM on Sep 11th 2006 by EM